Inaugural ASAS–CAAV Asia Pacif ic Rim Conference Abstracts

Lactation Biology PostersT278 Effect of increasing amounts of free linolenic acidT279 Milk composition variation during the early, mid,emulsion infused into the duodenum of lactating dairy cows on the and late lactation phase of dairy cows in Inner Mongolia. S. G. Jin* 1 , F.oxidative stability of milk fat. Q. S. Liu, J. Q. Wang*, D. P. Bu, E. Khas, H. Liu 1 , T. Wuliji 2 , and S. Jin 1 , 1 Inner Mongolia Agricultural University, Hohhot,Y. Wei, L. Y. Zhou, and K. L. Liu, State Key Laboratory of Animal Nutrition, Inner Mongolia, China, 2 University of Nevada, Reno, NV, USA.Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing,China.This experiment was conducted to compare milk composition variation of 3dairy breeds, Holstein, Simmental, and Sanhe cows, during early, mid, and latelactation phase by 4 district locations of Inner Mongolia. A total of 720 lactatingdairy cows (Holstein = 540; Simmental = 90; and Sanhe = 90) were sampledtwice during each of the defined lactation phases respectively. Milk DN (%),protein, fat, nonfat solids, lactose, and casein were determined for each milkingcow during lactation phase. The individual AA concentration, the ratio ofessential and nonessential AA groups, and total AA (TAA) were quantifiedby an automated AA analyzer. Milk compositions were presented for breeds,locations, and lactation phases. Data were primarily analyzed using the SPSSstatistical program and differences among means were compared by Duncan’smultiple range test procedure. Milk protein content was averaged for 3.19, 3.11,3.37, and 3.31% for district of Bayannur, Hohhot, Tongliao, and Hulunbuir,respectively. There was no difference in milk DM, lactose, and casein contentamong district locations. Major nutrient composition and TAA of milk werehigher in the early and later lactation (P < 0.05) than the mid lactation phase byall 3 dairy breeds (Table 1). Overall, Simmental and Sanhe cows had producedhigher milk DM content and milk fat (P < 0.05) than those of the Holstein.The objective of this study was to determine the effects of increasing amountsof high linolenic acid mixture emulsion infused into the duodenum of dairycows on milk fatty acid profile and the susceptibility of milk fat to oxidation.In a crossover design, 4 multiparous Holstein cows (BW = 556 ± 19 kg, DIM= 93 ± 9 d) fitted with duodenal cannulas were administered 2 treatments.Treatments were duodenally infused with increasing amounts (0, 30, 60, 90,or 120 g/d) of free linolenic acid (FLNA) emulsion from high-linolenic perillafatty acid or control with carrier alone. Continuous infusions (20 to 22 h/d)were for 7 d at each amount. Infusions were homogenates of free linolenic acidwith 15 g/d of xanthan gum, 5 g/d of sodium alginate, and 25 g/d of Tween 80in 10 L of tap water; controls received carrier only. Each period lasted 5 wk;during period 1, the 2 cows received each FLNA amount (0, 30, 60, 90, and120 g/d) sequentially, each for 1 wk, and the 2 control cows received only thecarrier infusate for the entire 5 wk. In period 2, the procedures were repeated.Data were analyzed statistically by using PROC MIXED of SAS. The contentof PUFA (3.85, 10.45, 16.53, 23.67, and 30.44%), especially α-linolenic acid,in milk fat increased linearly with FLNA infusion (0.61, 6.49, 12.42, 18.75, and25.38%). However, the saturated fatty acids decreased linearly (74.85, 70.13,66.93, 62.20, and 55.98%). The activity of superoxide dismutase, glutathioneperoxidase, and catalase tended to decrease quadratically (P = 0.05, 0.09,and 0.10, respectively), but the concentration of malondialdehyde increasedquadratically (P = 0.005) in milk fat of treatment samples (3.60, 3.63, 3.53,3.87, and 3.79 nmol/mL for 0, 30, 60, 90, and 120 g/d of FLNA, respectively).Results suggest that the polyunsaturated fatty acids in the milk fat can be alteredby the FLNA supplementation into the small intestine of dairy cows (≤120 g/d),but this variation would decrease the oxidative stability of milk fat.Key Words: oxidative stability, free linolenic acid, milk fatTable 1. Nutrient composition and total amino acids (TAA) of milkproduced in the early, mid, and late lactation phasesBreed Composition, % Early Mid Late lactationHolstein Fat 3.6 b 3.1 a 3.9 bProtein 3.4 b 3.1 a 3.4 bDM 11.4 ab 11.1 a 11.6 bTAA (mg/100 mg) 2.7 b 2.6 a 2.9 cSimmental Fat 4.7 b 3.5 a 4.8 bProtein 3.2 b 3.1 a 3.4 bDM 13.9 b 12.9 a 14.1 bTAA 2.7 b 2.6 a 2.8 bSanhe Fat 4.4 b 3.2 a 4.5 bProtein 3.4 b 3.1 a 3.5 bTM 12.8 b 11.9 a 12.8 bTAA 2.7 b 2.7 a 3.0 ca–cMeans bearing a different superscript differ at P < 0.05 within rows.Key Words: milk composition, lactation, Holstein79